Spacer for electrical windings



y 1961 s. R. CARLON 2,986,716

SPACER FOR ELECTRICAL WINDINGS Filed 001;. 18, 1957 United States PatentSPACER FOR ELECTRICAL WINDINGS Steven R. Carlon, Pittsfield, Mass.,assignor to General Electric Company, a corporation of New York FiledOct. 18, 1957, Ser. No. 691,081

4 Claims. (Cl. 336185) This invention relates to stationary electricalinduction apparatus, and more in particular to an improved spacingarrangement for axially spacing disc-shaped coils for transformers andthe like.

In one form of transformer, the windings are comprised of a plurality ofaxially displaced disc-shaped coils, the coils generally although notnecessarily being serially connected. Each of the disc-shaped coilscomprises one or more conductor turns. The coils surround a cylindricalwinding member of insulating material, and elongated axially extendingspacing members separate the coils from the winding cylinder to providecooling ducts. The coils are axially displaced from one another in orderto provide for proper cooling as well as to insure sufficient insulationtherebetween, and in order to maintain the separation of the coilsagainst mechanical displacement or displacement caused byelectromagnetic forces within the transformer, it is customary to insertradially extending spacers between the coils.

In the past, various means have been employed for axially spacing thecoils. In one conv ntional spacing arrangement, the axially extendingspacing members, commonly known as tie strips, have a generally T-shapedcross section with the widest portion of the spacing member, i.e., thecross arm, being away from the winding cylinder and engaging theradially inner surfaces of the coils. Flat generally rectangularinsulating spacers are provided with their radially inner edges havingapertures that engage the T-shaped axially extending members tointerlock the radially extending members against pivotal and radialmovement. In other words, the flat radially extending spacers, commonlyreferred to as key spacers,

are provided with apertures in the radially inner end that match thecross section of the axially extending members or tie strips.

In this arrangement, the key spacers are only held in position by thesmall projections engaging the tie strips, and these projections maybecome broken due to excessive pounding of the spacers that may arise,for example, from arc-bac in rectifier transformers, or from shortcircuiting of the electrodes connected to arc furnace transformers. Whenthe projections of the key spacers become broken, the key spacers mayfall out of the windings, with consequent damage to the transformer dueto possible axial contact between adjacent coils or fouling of thecirculation pumps of the transformer by the broken spacer The breakingof the projections of the key spacers is believed to be due to pivotalmovement of the key spacer about the tie strip, commonly known aswalking, resulting for example from unequal movement of the conductorsof the coils engaging the key spacers when excessive current in thetransformer produces radial forces within the transformer tend toradially expand the windings. That is, when a transformer winding issubject to excessive current conditions, the windings tend to expandradially, and if the conductors are not wound with the same tension,slight circumferential movement may occur between adjacent conductors,and this movement may result in circumferential movement of the keyspacer.

In order to prevent such movement of the key spacers, axially extendingmembers having channel-shaped cross sections have been provided engagingthe radially outer extremities of the key spacers. This arrangement hasnot, however, provided a satisfactory solution to the problem, since thechannel-shaped members were relatively expensive, and it was necessaryto manually tie the channel-shaped members to the windings. In addition,the channel-shaped members did not sufficiently hold the key spacers toentirely prevent the breaking and falling out of the key spacers.

It is therefore an object of this invention to provide an improved meansfor axially spacing disc-shaped coils of an electrical winding.

It is also an object to provide locking means for preventing breakingand falling out of key spacers in an electrical winding, the lockingmeans being characterized in that it is economically provided, and doesnot require manual tying to the winding.

Briefly stated, in accordance with one aspect of my invention, I providea winding for an electrical induction apparatus such as a transformer orreactor. The winding is comprised of a plurality of axially aligneddisc-shaped coils disposed on a winding cylinder. A plurality ofelongated axially extending spacing members space the coils from thecylinder to provide cooling ducts therebetween. Radially extendingspacing means are provided for axially spacing the coils. Axiallyextending locking strip means are provided circumferentially alignedwith the axially extending spacing members radially outwardly of thecoils, and the radial ends of the radially extending spacers arecircumferentially, radially and pivotally interlocked with the axiallyextending spacing members and the locking strip members.

While the specification concludes with claims particularly pointing outand distinctly claiming a subject matter which I regard as my invention,it is believed that the invention will be better understood from afollowing description taken in connection with the accompanying drawing.

In the drawing:

Fig. 1 is a perspective view of a portion of a winding embodying thecoil spacing arrangement of one aspect of my invention,

Fig. 2 is a partially cross-sectional top view of the winding of Fig. 1with the upper key spacers removed,

Fig. 3 is a top view of a key spacer of the windings of Figs. 1 and 2and Figs. in 4 and 5 are top views of variations of the key spacer ofFig. 3.

Referring now to the drawing, and more in particular to Fig. 1, thereinis illustrated an electrical winding comprising a plurality ofdisc-shaped coils 10, 11, and 12. The coils are axially aligned andsurround an insulating cylinder 13. A plurality of axially extendingelongated spacing members such as tie strips 14 are provided on theouter circumference of the winding cylinder 13 to space the coils fromthe cylinder and provide a cooling duct therebetween. The spacingmembers 14 are preferably equally spaced circumferentially about thecylinder *13. The winding cylinder 13 may surround a magnetic coil (notshown) according to the conventional practice.

The coils 10, 11 and 12 are axially spaced apart by substantially flatradially extending insulating spacing members such as key spacers 15. Asmore clearly illust-rated in Fig. 2, the tie strips 14 may have T-shapedcross sections with the Widest portion of the tie strips being away fromthe winding cylinder 13 and engaging the radially inner edges of thecoils. An aperture 20 is provided in the inner radial extremity of eachkey spacer 15, the aperture 20 being shaped the same as and at leastpartially surrounding the tie strip 14 so that the key spacer 15 isinterlocked with the tie strip to prevent circumferential and radialmovement of the spacer 15 with respect to the winding, as well aspivotal movement about the tie strip.

Elongated locking strip members 21 are Provided circumferentiallyaligned with the tie strips 14 radially outwardly of the coils.Apertures 22 are provided in the radially outer extremities of thespacers 15 that at least partially surround the locking strip member 21to interlock the spacers 15 to the locking strips 21 and thereby providecircumferential, radial and pivotal interlocking of the spacers 15 andthe locking strips 21. As illustratetd in Figs. 1 and 2, the lockingstrip 21 may have a substantially rectangular cross section with thewidest side tangential to the coils, and the aperture 22 in the spacer15 may be shaped to engage the radially inner surface portion of theradially outer surface of the locking strip 21. The locking strips 21preferably do not contact with the radially outer edges of the coils, inorder to allow for radial expansion of the coils.

While the preferred shapes of the tie strips, key spacers, and lockingstrips, are substantially as illustrated in Figs. l3, it is obvious thatother shapes may be provided for these components without departing fromthe spirit or scope of my invention. Thus, any non circular shape may beprovided for the apertures in the spacers 15, and the cross sections ofthe tie strips and locking strips may have any non-circular shapeas'long as the members co-act to prevent the pivotal, radial and circumferential movement of the spacers 15. Thus, as illustrated in Fig. 4,the aperture 22 in the member.15 may be similar to the aperture of thekey spacer of Fig. 3 with the exception that it is completely enclosed.In this variation, the locking strip employed is preferably the same asthe locking strip illustrated in Figs. 1 and 2. In another variation, asillustrated in Fig. 5, the aperture 22 in the member 15 may betrapezoidal in shape, with the larger base forming the radially inneredge of the aperture. In this latter case, it is of course preferablethat the locking strip also be trapezoidal in cross section to conformto the shape of the aperture in the spacer 15.

Since, in the spacing arrangement of my invention, the radiallyextending spacing members are positively locked on both ends frommovement in the circumferential and radial directions with respect tothe transformer and pivotally about the locking strips and the tiestrips, there is no danger that the projections of the radiallyextending spacing members will be broken as a result of internal forcesdue to excess current flowing through the transformer windings.

It will be understood, of course, that, while the forms of my inventionherein shown and described constitute preferred embodiments of theinvention, it is not intended herein to illustrate all of the possibleequivalent forms or ramifications thereof. It will also be understoodthat the words used are words of description rather than of limitation,and that various changes may be made without departing from the spiritor scope of the invention herein disclosed, and it is aimed in theappended claims to cover all such changes as fall within the true spiritand scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Electrical induction apparatus of the type having a plurality ofaxially aligned disc-shaped winding coils that radially expand whenexcessive current passes therethrough, an insulating cylinder, saidcoils surrounding said insulating cylinder, a plurality of axiallyextending spacing members circumferentially disposed on said cylinderand radially spacing said coils from said cylinder, a plurality ofradially extending spacing members disposed between said coils, saidradially extending spacing members separating said coils axiallyalongsaid cylinder, said radially extending spacing members being ofsubstantially uniform thickness and having substantially flat smoothouter surfaces that permit radial movement of said coils therealong,axially extending locking strips circumferentially aligned with saidaxially extending spacing members and disposed radially outwardly ofsaid coils a distance sufficient to permit said coils to radially expandwith excessive current, said radially extending spacing members havingnon-circular apertures in their inner and outer radial extremities atleast partially surrounding said axially extending spacing members andlocking strips, said apertures and the cross sections of said axiallyextending spacing members being shaped to prevent radial andcircumferential movement of said radially extending spacing members withrespect to said winding and pivotal movement of said radially extendingspacing members with respect to the radial extremities thereof, wherebyfracturing of said radially extending spacing members on expansion ofsaid coils is prevented.

2. The winding of claim 1 in which said axially extending spacingmembers have substantially T-shaped cross sections with the widestdimension radially outwardly and engaging the radially inner edges ofsaid coils, the apertures in said radially extending spacing members aresubstantially T-shaped with the widest dimension toward the centers ofthe members, and the locking strip means have substantially rectangularcross sections with the longest width substantially tangential to saidcoils.

3. The winding of claim 1 in which said axially extending spacingmembers have substantially T-shaped cross sections with the widestdimension radially outwardly and engaging the radially inner edges ofsaid coils, said locking strip means have substantially rectangularcross sections with the longest width substantially tangential to saidcoils, and the apertures in said radially extending spacing memberspartially surround said axially extending spacing members and completelysurround said locking strip means.

4. The winding of claim lin which said axially extending spacing membershave substantially T-shaped cross sections with the widest dimensionradially outwardly and engaging the radially inner edges of said coils,said locking strip means have substantially trapezoidal cross sectionswith the longest base toward said coils, and the apertures in saidradially extending members at least partially surround and conform tothe shape of said axially extending members and locking strip means.

References Cited in the file of this patent UNITED STATES PATENTS1,241,549 Peters Oct. 2, 1917 2,201,005 Ford May 14, 1940 2,745,073Swidelsky May 8, 1956

